"Does not the word SUPERNATURAL really mean FICTIONAL?"

Theists argue that in contrast to our natural world, gods are supernatural and part of some supernatural world. The distinction is very convenient for believers; yet the word ‘supernatural’ exists only because it was conceived by them.

The truth is that the notion of “the supernatural” is itself a wholly human invention, no less than Bertrand Russell’s orbiting teapot is a human invention---and whose 'orbiting-teapot level' of reality in our wondrous natural Universe is exactly zero.

We know that the 'natural' is actuality, reality, rationality. We find it everywhere we look.

By contrast, the 'supernatural' is not at all what the dictionaries define it as. Probably all dictionaries were written by religious believers.

Definitions from the Oxford English Dictionary exemplify:
Supernatural as adjective. "That is above nature; transcending the powers or the ordinary course of nature."
Supernatural as noun: "That which is supernatural." . . . etc.

Such definitions presuppose that there is a ‘supernatural’, and therefore what is not natural is supernatural---whereas I equate the word ‘supernatural’ with ‘fictional’ because the ‘supernatural’ is no more than an idea, a hypothesis, an unnecessary concept.

In short, the 'supernatural' is nothing but religious-fictional nonsense.

‘Supernatural’ means fictional, and we should say so to theists when put to the argument.

Consequently, instead of allowing them to assert that everything is either natural or supernatural, we should correct them by saying that everything is either natural or fictional.

I agree fictional could fit right in (coincidently right after fairy). The word magical always pops in my head when I hear supernatural. "It's so MAGICAL!" I think the flip side of the supernatural coin is "faith". You really can't have one without the other. They are a giant deadweight, leftover from ancient and relatively ignorant cultures, that humanity keeps dragging along.

Ah, but religious people often don't make the connection between their beliefs and the supernatural. To them, "supernatural" means casting spells, seeing ghosts, telling fortunes...in other words, cultish and new agey stuff, not that old time religion. They will often deny any belief in the supernatural. The fact that their holy scripture is full of spells, ghosts and prophecies seems to escape them; their religion is exempt from their own skepticism.
To maybe clarify without really disagreeing: supernatural can indeed mean fiction, but often it is a fictitious explanation for a real event (like God causing earthquakes). As I've long said, lacking real information, people will make stuff up and believe it.

Ah but there are material differences, some subtle, in how phrases and definitions can be constructed.
To begin with, if I was given the job of revising, as I consider necessary, the OED definition of 'supernatural' I might try:
Supernatural as adjective. "That which is claimed to be above nature; that which is claimed to transcend the powers or the ordinary course of nature."

[instead of the OED's "That is above nature; transcending the powers or the ordinary course of nature."]

Next, the graviton is far from being any "mumbojumbo" and "work of fiction" like the purported word 'supernatural' arguably is.
The 'graviton' is a seriously-argued proposition emanating from the brains and pens of theoretical physicists with much real knowledge from other fields to help support it. What is more, tests can be advanced and maybe one day detection will be possible.

I find separations like natural versus supernatural very slippery. Most people see their perspectives as natural. In my courses on atheism/agnosticism I'd talk about naturalists (like me) believing in a natural world and religious people accepting the natural world and then believing in another one as well, a supernatural reality. I think that separation is artificial and very much from a naturalist's perspective.

Probably what I was saying is that naturalists accept that part of reality accessible by empirical means supported by human reason (as done, for example, by the natural sciences, most social sciences, and historical research). Stuff outside of that is then been branded 'supernatural'. Of course empirically-based reality expands and contracts and even changes fundamentally as our understandings shift. Kuhn rightfully said that all we can say about paradigm shifts is our scientific world-view has changed and not that we are close to 'truth'. The mechanistic view of existence no longer is part of the modern science view and is therefore now a fiction. That was not so to earlier scientists. All this tells me to be humble in our claims and not to be just as self-righteous as the religious people we condemn.

The whole damn dictionary needs to be re-written, quite frankly. All of them. Languages are woefully inadequate and full of logical inconsistencies. They need to be written by physicists and logicians that thye might be useful for actually describing reality.

I dunno, being but a layman, yet the term seems like it could apply if only in reference to what appears so. Such as a black hole having a gravitational pull of -almost- supernatural strength. Or an autistic with a mathematical prowess of -near- supernatural proportions. Both are natural, but exceedingly unusual. Let's not write off (mwaha!) a term just because it is commonly used by the credulous.